feat: batch video upscaling with folder upload, directory save, and result comparison (#1051)

* feat: support batch video upscaling with folder upload and directory save

- Add multi-file selection and entire folder upload (webkitdirectory)
- Support drag & drop of both files and folders via FileSystemEntry API
- Add save directory picker using File System Access API (showDirectoryPicker)
- Process videos sequentially with per-file progress and status tracking
- Add right-side result list with click-to-compare functionality
- Add per-video duration and total batch duration display
- Add retry button for failed items with error detail display
- Remove auto-play on comparison viewer load
- Fix worker error handling: handle "error" command to reject stale promises
- Fix event listener accumulation in video comparison (AbortController)
- Fix XSS risk by escaping HTML in all innerHTML injections
- Fix URL revocation timing in download to prevent large file truncation
- Extract writeToSaveDirectory and truncateName helpers to reduce duplication
- Add Usage Guide panel explaining single/multiple/folder upload options

Files changed:
  docs/upscaler/index.html  (+1110/-181)
  docs/upscaler/upscaler.js (+110)

* fix: prevent auto-play and resource consumption during upscaling

- Set preload="metadata" on preview and comparison video elements
- Explicitly pause preview video after setting src in showVideoPreview
- Remove preview video seek sync from batch processing progress callbacks
  (was causing continuous decode during upscaling, wasting GPU resources)
- Remove preview video seek sync from retry progress callback
- All videos now require manual play; no background resource usage

* fix: improve upscaled video quality with higher bitrate and codec support

- Raise base bitrate from 2.5 Mbps (25e5) to 8 Mbps (8e6) for standard and
  firefox processors, preventing quality loss when source videos have high
  bitrates (e.g. 720p @ 16.7 Mbps was producing 1440p @ 10 Mbps, smaller
  than the original file)
- Double the bitrate for mediabunny processor (X.n1 * 2) to account for the
  4x pixel increase from 2x upscaling
- Add H.264 Level 5.1 (avc1.640033) and Level 5.2 (avc1.640034) codecs to
  the fallback lists, since Level 4.0 (avc1.640028, ~24.6 Mbps) cannot
  support the higher bitrates for 1440p+ outputs
- Add latencyMode: "quality" to VideoEncoder configs for both standard and
  firefox processors, prioritizing encoding quality over latency (suitable
  for offline processing)

* feat: add video data comparison panel for original vs upscaled metrics

- Add a comparison data table below the file info bar showing 6 metrics:
  Resolution, File Size, Duration, Est. Bitrate, Pixels, Process Time
- Display per-metric change percentage with color-coded indicators:
  green (↑) for improvements, red (↓) for regressions, gray for neutral
- Estimated bitrate calculated from file size × 8 / video duration
- Table renders after both original and upscaled video metadata loads
- Auto-hide panel on reset

* fix: make video data comparison panel full-width and responsive

- Move comparison data table from inside the left column to the full-width
  area below the left/right layout, so it is no longer constrained by the
  comparison viewer column width
- Remove table-fixed colgroup and overflow-x-auto that caused horizontal
  scrolling on smaller screens
- Table now uses w-full auto-layout, displaying all 4 columns (Metric,
  Original, Upscaled, Change) without requiring horizontal scrolling

---------

Co-authored-by: rionzhao <rionzhao@tencent.com>

assets/@mediapipe/selfie_segmentation/selfie_segmentation_solution_wasm_bin.js

@@ -0,0 +1,21 @@
+
+var createMediapipeSolutionsWasm = (() => {
+  var _scriptDir = typeof document !== 'undefined' && document.currentScript ? document.currentScript.src : undefined;
+  if (typeof __filename !== 'undefined') _scriptDir = _scriptDir || __filename;
+  return (
+function(createMediapipeSolutionsWasm) {
+  createMediapipeSolutionsWasm = createMediapipeSolutionsWasm || {};
+
+var Module=typeof createMediapipeSolutionsWasm!="undefined"?createMediapipeSolutionsWasm:{};var readyPromiseResolve,readyPromiseReject;Module["ready"]=new Promise(function(resolve,reject){readyPromiseResolve=resolve;readyPromiseReject=reject});["_main","_fflush","___getTypeName","__embind_initialize_bindings","onRuntimeInitialized"].forEach(prop=>{if(!Object.getOwnPropertyDescriptor(Module["ready"],prop)){Object.defineProperty(Module["ready"],prop,{get:()=>abort("You are getting "+prop+" on the Promise object, instead of the instance. Use .then() to get called back with the instance, see the MODULARIZE docs in src/settings.js"),set:()=>abort("You are setting "+prop+" on the Promise object, instead of the instance. Use .then() to get called back with the instance, see the MODULARIZE docs in src/settings.js")})}});var moduleOverrides=Object.assign({},Module);var arguments_=[];var thisProgram="./this.program";var quit_=(status,toThrow)=>{throw toThrow};var ENVIRONMENT_IS_WEB=typeof window=="object";var ENVIRONMENT_IS_WORKER=typeof importScripts=="function";var ENVIRONMENT_IS_NODE=typeof process=="object"&&typeof process.versions=="object"&&typeof process.versions.node=="string";var ENVIRONMENT_IS_SHELL=!ENVIRONMENT_IS_WEB&&!ENVIRONMENT_IS_NODE&&!ENVIRONMENT_IS_WORKER;if(Module["ENVIRONMENT"]){throw new Error("Module.ENVIRONMENT has been deprecated. To force the environment, use the ENVIRONMENT compile-time option (for example, -sENVIRONMENT=web or -sENVIRONMENT=node)")}var scriptDirectory="";function locateFile(path){if(Module["locateFile"]){return Module["locateFile"](path,scriptDirectory)}return scriptDirectory+path}var read_,readAsync,readBinary,setWindowTitle;function logExceptionOnExit(e){if(e instanceof ExitStatus)return;let toLog=e;if(e&&typeof e=="object"&&e.stack){toLog=[e,e.stack]}err("exiting due to exception: "+toLog)}if(ENVIRONMENT_IS_NODE){if(typeof process=="undefined"||!process.release||process.release.name!=="node")throw new Error("not compiled for this environment (did you build to HTML and try to run it not on the web, or set ENVIRONMENT to something - like node - and run it someplace else - like on the web?)");var fs=require("fs");var nodePath=require("path");if(ENVIRONMENT_IS_WORKER){scriptDirectory=nodePath.dirname(scriptDirectory)+"/"}else{scriptDirectory=__dirname+"/"}read_=(filename,binary)=>{filename=isFileURI(filename)?new URL(filename):nodePath.normalize(filename);return fs.readFileSync(filename,binary?undefined:"utf8")};readBinary=filename=>{var ret=read_(filename,true);if(!ret.buffer){ret=new Uint8Array(ret)}assert(ret.buffer);return ret};readAsync=(filename,onload,onerror)=>{filename=isFileURI(filename)?new URL(filename):nodePath.normalize(filename);fs.readFile(filename,function(err,data){if(err)onerror(err);else onload(data.buffer)})};if(process["argv"].length>1){thisProgram=process["argv"][1].replace(/\\/g,"/")}arguments_=process["argv"].slice(2);process["on"]("uncaughtException",function(ex){if(!(ex instanceof ExitStatus)){throw ex}});process["on"]("unhandledRejection",function(reason){throw reason});quit_=(status,toThrow)=>{if(keepRuntimeAlive()){process["exitCode"]=status;throw toThrow}logExceptionOnExit(toThrow);process["exit"](status)};Module["inspect"]=function(){return"[Emscripten Module object]"}}else if(ENVIRONMENT_IS_SHELL){if(typeof process=="object"&&typeof require==="function"||typeof window=="object"||typeof importScripts=="function")throw new Error("not compiled for this environment (did you build to HTML and try to run it not on the web, or set ENVIRONMENT to something - like node - and run it someplace else - like on the web?)");if(typeof read!="undefined"){read_=function shell_read(f){return read(f)}}readBinary=function readBinary(f){let data;if(typeof readbuffer=="function"){return new Uint8Array(readbuffer(f))}data=read(f,"binary");assert(typeof data=="object");return data};readAsync=function readAsync(f,onload,onerror){setTimeout(()=>onload(readBinary(f)),0)};if(typeof scriptArgs!="undefined"){arguments_=scriptArgs}else if(typeof arguments!="undefined"){arguments_=arguments}if(typeof quit=="function"){quit_=(status,toThrow)=>{logExceptionOnExit(toThrow);quit(status)}}if(typeof print!="undefined"){if(typeof console=="undefined")console={};console.log=print;console.warn=console.error=typeof printErr!="undefined"?printErr:print}}else if(ENVIRONMENT_IS_WEB||ENVIRONMENT_IS_WORKER){if(ENVIRONMENT_IS_WORKER){scriptDirectory=self.location.href}else if(typeof document!="undefined"&&document.currentScript){scriptDirectory=document.currentScript.src}if(_scriptDir){scriptDirectory=_scriptDir}if(scriptDirectory.indexOf("blob:")!==0){scriptDirectory=scriptDirectory.substr(0,scriptDirectory.replace(/[?#].*/,"").lastIndexOf("/")+1)}else{scriptDirectory=""}if(!(typeof window=="object"||typeof importScripts=="function"))throw new Error("not compiled for this environment (did you build to HTML and try to run it not on the web, or set ENVIRONMENT to something - like node - anLine truncated
+
+
+  return createMediapipeSolutionsWasm.ready
+}
+);
+})();
+if (typeof exports === 'object' && typeof module === 'object')
+  module.exports = createMediapipeSolutionsWasm;
+else if (typeof define === 'function' && define['amd'])
+  define([], function() { return createMediapipeSolutionsWasm; });
+else if (typeof exports === 'object')
+  exports["createMediapipeSolutionsWasm"] = createMediapipeSolutionsWasm;